The present invention relates to a container for storing fine particle, and a product for storing fine particle, and also to a container for storing toner, a product for storing toner, and a device for supplying toner all of which are loaded in an electrophotographic image forming apparatus such as a copying machine or a printer, as a form of a cartridge.
Concerning the method for supplying toner to an image forming apparatus of employing electrophotography, there are several kinds of types which are not only a toner cartridge wherein the toner storing cartridge itself is loaded in an image forming apparatus, but also the container which is opened and the contained toner is supplied to the image forming apparatus. These toner storage containers are designed in such a way that the operator's hands or the interior of the image forming apparatus do not become dirty when the toner is supplied to the image forming apparatus.
In recent years, containers have been made of resins, being resistant to deformation or brockage, and can be recycled. When the toner storage container is retrieved after use, toner is again filled into the retrieved container, and the container is shipped to be circulated, which is predominantly the current system. Further, the resin container has stability of size, and excellent sealing performance, spillage of toner from the container is very rare.
However, when the storage container is filled with toner in a factory, the interior pressure of the storage container is kept at the pressure in the factory, and when temperature rises at the user's location, the interior pressure of the stored contents may rise higher than the ambient pressure. When the storage container is opened during installation, toner in the storage container will be expelled strongly by the pressure difference, and the expelled toner will pollute the user and the apparatus. Therefore, when the user changes the cartridge whose interior pressure is high on a hot day during the summer season, the problems of pollution exist.
Further, among the various kinds of fine particles or grainy materials, for example, edible powder such as ground coffee beans or instant juices, these materials may produce gas during storage. If the gas generated from the stored fine particles or grainy materials is not expelled from the storage container before opening, there is a strong possibility that the interior of the storage container will expand and be destroyed, which lessens the commercial value of the fine particles or grainy materials.
For the above-mentioned problems, in order to reduce the interior pressure of the storage container, proposed have been an air permeable film or a venting valve incorporated with the storage container, or a lid member formed of a flexible material or a porous material. However, due to additional new parts or an increase in the number of manufacturing processes, a rise in cost is unavoidable.
Further, by using a means which does not generate a pressure difference between interior and exterior of the container, resulting in exposal of the fine particles into the environment for a relatively long period, it is not preferable from the view point of conservation of quality of the product over a long term. For example, in case of toner for electrophotography, the electrostatic property of the toner is changed under influence of the external environment. When a cartridge storing such toner is employed for the image forming apparatus, it is not possible to obtain an expected high quality of the image, because the toner's electrostatic property has been altered. Further, in case of food products such as powdered juice, taste will be different, because of quality deterioration through oxidization.
Concerning the matter that the interior pressure of the container becomes higher, proposed has been a method wherein the interior pressure of the container is reduced. For example, in patent document 1, disclosed is technology wherein when the interior pressure of the container is increased, an air passing condition is partially formed by use of a wall of a cap which can be elastically deformed, and which in turn decreases the interior pressure.
[patent document 1] TOKKAIHEI 6-208301
However, according to the technology disclosed in patent document 1, it is understood that the degree of deformation of the cap wall varies so widely that it is not possible to effectually reduce the interior pressure, or too much deformation occurs and the toner is expelled.
Further, there is a method wherein an air permeable material is attached on the container to reduce the interior pressure of the container, however this method requires an additional member to be attached, which increases the production cost and the number of manufacturing processes, still further, the container is easily affected by exterior conditions, because of the permeability of air, and thereby it is very difficult to maintain the quality of the contained fine particles, over the long term. In the case of toner for electrophotography, for example, the electrostatic property is changed so greatly that the expected high quality of the image cannot be obtained, resulting in unacceptable image formation. Further, in the case of the finely ground food, the quality of the food can be severely deteriorated by oxidization.
As mentioned above, in the case of the finely ground products to be stored such as fine particle toner, it is very difficult technology to stably maintain the quality of the stored fine particles over the long term, and to reduce the difference of pressure between the interior and exterior of the container, and further to prevent expelling of the fine particles from the container when the container is opened.